A renewed Middle East war could be the first foreign policy crisis to test President-elect Barack Obama's mettle when he takes office next month.

Or it could be President Bush's last crisis before he leaves office. That's how fast tensions between Israel and Hamas are heating up.

Hamas, the Iran-sponsored Islamist terrorist group that currently rules Gaza, recently marshaled hundreds of thousands of supporters in Gaza City to brag about its violent exploits and to celebrate the group's founding 21 years ago. Meanwhile, Hamas' top leaders made two important announcements:

First, the six-month truce with Israel that was coming to an end would not be renewed. Second, on Jan. 8 Hamas will stop recognizing the legitimacy of Palestinian President Mahmoud Abbas, who holds sway over the West Bank.

After Israel withdrew from Gaza as a goodwill gesture in peace talks with Abbas, Hamas waged war for months against the Palestinian president's Fatah forces before winning control of Gaza in 2007. Hamas is sworn to destroy Israel and, until the truce was agreed on, was involved in dozens of suicide bombings that killed more than 250 Israelis.

Since the truce ended about a week ago, Hamas has launched rocket and mortar fire into Israel, prompting a response from Israeli defense forces. The renewed hostilities have drawn promises to break Hamas' hold on Gaza from the two frontrunners contending to become Israel's next prime minister in February's elections.

"Israel must topple Hamas rule in Gaza and a government under my command will do just that," vows Foreign Minister Tzipi Livni, leader of the governing Kadima party. Not to be outdone, Benjamin Netanyahu, leader of the rival Likud party, says there's "no choice but to topple Hamas... Right now we have to go from passive response to active assault."

It could be that Iran is pushing Hamas into a confrontation with Israel in hopes of dividing Israelis into peace and war camps going into February's elections. So far, based on frontrunners' responses, it doesn't seem to be working.

Radical Islamists may also be seeking to take advantage of perceived U.S. weakness during the presidential transition. They shouldn't have much luck there either, as there seems to be no daylight between Bush and Obama as far as Hamas is concerned. Both men agree with official U.S. designation of Hamas as a terrorist group. Even so, renewed warfare would still pose a serious challenge to U.S. diplomacy and influence around the world.

Further complicating, if not inflaming, Mideast tensions is America's worst-ever former president, Jimmy Carter. While Hamas was issuing threats against Abbas and terminating the truce with Israel, Carter was "talking peace" in Syria with Hamas' exiled political leader, Khaled Meshaal -- the second time in a year he's done that, drawing condemnation from both the U.S. and Israeli governments, and for good reason.

The problem with Carter stirring the Mideast cauldron is that as an ex-president and Nobel Peace Prize winner, he gives the impression that his anti-Israel, pro-Palestinian and soft-on-jihad views are shared by the U.S. government when they clearly are not.

Carter could best serve his nation by going back to Plains and growing peanuts again.