MacDILL AIR FORCE BASE, Fla. — The Obama administration plans to bolster the American military presence in the Persian Gulf after it withdraws the remaining troops from Iraq this year, according to officials and diplomats. That repositioning could include new combat forces in Kuwait able to respond to a collapse of security in Iraq or a military confrontation with Iran.

The plans, under discussion for months, gained new urgency after President Obama’s announcement this month that the last American soldiers would be brought home from Iraq by the end of December. Ending the eight-year war was a central pledge of his presidential campaign, but American military officers and diplomats, as well as officials of several countries in the region, worry that the withdrawal could leave instability or worse in its wake.

After unsuccessfully pressing both the Obama administration and the Iraqi government to permit as many as 20,000 American troops to remain in Iraq beyond 2011, the Pentagon is now drawing up an alternative.

In addition to negotiations over maintaining a ground combat presence in Kuwait, the United States is considering sending more naval warships through international waters in the region.

With an eye on the threat of a belligerent Iran, the administration is also seeking to expand military ties with the six nations in the Gulf Cooperation Council — Saudi Arabia, Kuwait, Bahrain, Qatar, the United Arab Emirates and Oman. While the United States has close bilateral military relationships with each, the administration and the military are trying to foster a new “security architecture” for the Persian Gulf that would integrate air and naval patrols and missile defense...