Cnooc Ltd.'s unsolicited $18.5 billion offer to buy Unocal Corp. on June 22, following an earlier bid by Chevron Corp., kicked Washington's public policy machinery into high gear.

* June 23 -- Senate Finance Committee holds hearing on U.S.-China economic relations.

* June 24 -- Rep. William J. Jefferson (D-La.) and 40 other House members release a letter demanding a security review.

* June 27 -- Reps. Joe Barton (R-Tex.) and Ralph M. Hall (R-Tex.) write to President Bush expressing "deep concern."

* June 30 -- House approves a resolution demanding a national security review.

* July 1 -- Cnooc formally requests a national security review by the Committee on Foreign Investment in the United States.

* July 6 -- Cnooc Chairman Fu Chengyu publishes "Why Is America Worried?" in Wall Street Journal.

* July 12 -- Chevron Chairman David J. O'Reilly responds with "Chevron's Pitch" in Wall Street Journal.

* July 12 -- Cnooc unveils advertising blitz for Capitol Hill newspapers.

* July 13 -- House Armed Services Committee holds hearing on the national security threat posed by Cnooc's bid.

* July 14 -- Carnegie Endowment for International Peace holds panel titled "Dark Clouds on the Horizon: Rising U.S.-China Frictions"

* July 15 -- Sen. Byron L. Dorgan (D-N.D.) introduces legislation that would prohibit the purchase of a U.S. energy company by a state-owned foreign corporation.

* July 19 -- House Energy and Commerce Committee to hold hearings on "China's bid for U.S. energy assets."

* July 20 -- Center for American Progress to hold panel on "China and the Geopolitics of Energy: Unocal and Beyond."