In a whirlwind week of change, President Barack Obama jettisoned Bush administration policy on greenhouse gases, shone an unforgiving light on its support for torture as an interrogation tactic and eased its restrictions on Cuba.
But there are limits, even to this new president's power, and a campaign pledge to seek a ban on assault weapons is an early casualty as a result.
And while the promise of change was arguably Obama's single most powerful asset in last year's campaign, the week demonstrated anew how carefully he calibrates its impact.
For years, they were a staple of sci-fi movies. Shining steel rail lines crisscrossing high above the cities of the future as passengers inside were whisked around at fantastic speeds.
Now, President Obama wants to make them real. He said so the other day as that inveterate Amtrak rider/supporter Vice-President Joe Biden stood beside him, salivating.
President Barack Obama promised Americans his administration would reform the "monstrous" U.S. tax system as millions faced the dreaded annual deadline on Wednesday for filing income tax returns.
Obama used Tax Day, a national ritual of public frustration due to the confusing tax code, to underscore his drive to cut taxes for many Americans while increasing spending to jolt the United States out of its worst recession in decades.
Once again, a president of the United States strode across a flattop and approached the microphones with unmistakable confidence. But this time the president was not walking across an aircraft carrier at sea, just a campus lecture hall stage in Washington.
Aiming to assert control over the nation's economic debate, President Barack Obama on Tuesday warned Americans eager for good news that "by no means are we out of the woods" and argued his broad domestic agenda is the path to recovery.
In a speech at Georgetown University, Obama aimed to juggle his recent glass-half-full takes on the economy with a determination to not be stamped as naive in the face lingering problems. He summarized actions his administration has taken to steady the limping economy and coupled that with a fresh overview of his domestic goals.
In a measured break with a half-century of U.S. policy toward communist Cuba, the Obama administration lifted restrictions Monday on Cuban-Americans who want to travel and send money to their island homeland.
In a further gesture of openness, U.S. telecommunications firms were freed to seek business there, too. But the broader U.S. trade embargo remained in place.
The triumphant end to the Somali pirate crisis let President Barack Obama sail unscathed out of a tricky political squall and may have earned him early stripes as US commander-in-chief.
The seizure by heavily-armed pirates of US merchant Captain Richard Phillips was widely portrayed in the US media as a first test of nerve for the new president, at a time when political critics were ready to pounce.
Finally, there comes an end to negotiations with international thugs.
The surgical removal by snipers to take out three of the pirates holding Capt. Richard Phillips wasn't without future risk to those who venture into the Indian Ocean but it may be the only approach the kidnappers from Somalia understand. And if it leads to more violence as hand wringers warn, it may just be the price of securing some freedom on the high seas. Furthermore, a decision to continue to negotiate rather than respond firmly undoubtedly would prolong the overall threat to shipping that has emboldened the brigands and made them wealthy with ransom money.
Defense Secretary Robert Gates, the Bush Cabinet officer who agreed to remain in place in the Obama administration, is demonstrating considerable policy courage.
So far, at least, he has shown himself to be a man for all seasons, politically speaking. In a very partisan time, with particularly intense rancor between Democrats and Republicans, he has been quite adept at bridging the great divide. Indeed, Gates is the first Pentagon head in history to continue in the post after an election resulted in a change in party in the White House.
President Barack Obama's visit to Mexico this week is a signal of support for President Felipe Calderon and his efforts to confront violent drug trafficking gangs, White House officials said on Monday.
The officials, briefing reporters on Obama's upcoming trip to Mexico and Trinidad, gave no indication the U.S. government was planning new initiatives on difficult issues like cross-border trucking or immigration before the visit.