Mikheil Saakashvili is a former president of Georgia, the former governor of Ukraine’s Odessa region and the leader of the political party Movement of New Forces.

Last week, during a short visit with my uncle’s family in the United States, I discovered that President Petro Poroshenko had stripped me of my Ukrainian citizenship in a quick and secret act that has left me stateless and without valid travel documents. He has also banned me from reentering the country.

What a difference a few months makes. It was only a little more than two years ago that the same president awarded me Ukrainian citizenship in a high-profile ceremony in Kiev. Before that, I served two terms as president of Georgia, turning a small and backward country into one that was singled out by the World Bank for the success of its reforms.

During my time in office, we succeeded in increasing Georgia’s gross domestic product by a factor of four, raising the state budget 11 times, eliminating corruption and red tape, and most important, paving the way for the region’s first democratic transfer of power.

After that, I chose to do something highly unusual: I decided to launch a political career in a second country, accepting Poroshenko’s offer to become the governor of Odessa, Ukraine’s biggest and most strategically significant region.

My job description was clear. I was tasked with cleaning up this traditionally corrupt region and uprooting the local mafia. Meanwhile, former members of my Georgian government were appointed to other high-level government positions, helping to create a new Ukrainian police force and the National Anti-Corruption Bureau of Ukraine, among other institutions.

After a good start, in collaboration with newly recruited young Ukrainian idealists, we began to run into trouble. Not only did the president cease to help in our efforts, but all too often he sided with the same entrenched interests we were supposed to be confronting. It soon became obvious that Poroshenko’s invitation to us was part of a public relations campaign to cast himself as a reformer in the eyes of the domestic public while also raising cash from international donors. In reality, he refused to challenge the oligarchic structure of Ukraine or to restrain his cronies.

After one and a half years of effort, I decided to give up on Poroshenko and officially resigned from my position as governor. I never intended to give up on the Ukrainian people, though, and I appealed to them directly by creating a new political party, the Movement of New Forces.

We were joined by elected representatives at every political level, as well as by many other figures who aimed to take on corruption and the oligarchs.

Although the presidential administration succeeded in blocking our access to all the main TV channels, I created my own talk show on a small private channel, rapidly turning it into one of the most-watched political programs in the country. Unfortunately, my program was temporarily pushed off the air in July — not long before Poroshenko stripped me of my Ukrainian passport.

As a legal basis, he cited cases started against me by the Georgian government, which is controlled by billionaire Bidzina Ivanishvili, a man with a long record of close business ties to Russia. No country in the world has recognized those cases, including Ukraine itself, whose prosecutor general’s office dismissed them as politically motivated two years ago.

It is obvious why Poroshenko acted so hastily, flouting any concern for due process of law; there were no hearings or legal process, and no prior notification was made. The entire decision was carried out in secret. Ukraine’s Constitution expressly prohibits the government from stripping any citizen of his or her nationality. This act clearly contradicts Ukraine’s international obligations, including those under the 1961 Convention on the Reduction of Statelessness. Here’s how Carl Bildt responded to Poroshenko’s decision on Twitter: “To deprive political enemies of citizenship is contrary to all principles.”

Whatever Poroshenko’s intentions, he cannot stop my political activities, and even less can he silence me. I will continue to mobilize my supporters in Ukraine to fight the rule of a corrupt and oligarchic elite, who have held the country back by plundering its best resources and undermining economic growth.

We are moving ahead with our plans to unite all pro-Western democratic forces. In the fall, we plan to launch a campaign to push for change in election legislation, to enforce the anti-corruption laws and to remove oligarchs from privileged access to the government.

Ukraine deserves so much more. I am committed to helping defend this great nation both from Russian President Vladimir Putin, who is undermining it from the outside, and from Poroshenko and the other oligarchs, who are destroying it from the inside. Even though I am barred from reentering Ukraine, I will continue to fight for my rights as a citizen and will continue to work for the best policies for the country.