Oil prices gained more than 2% on Monday after a resumption of military action between the U.S. and Iran rekindled market concerns about global supply disruption, as the conflict extended into its sixth month.

Brent crude futures were up $2.17, or 2.46%, to $90.27 a barrel at 12:12 p.m. EDT (1612 GMT). U.S. West Texas Intermediate crude was up $2.06, or 2.47%, to $85.46. Brent rose as high as $91.52 during the session, its highest since August 25.

U.S. President Donald Trump was quoted on Monday as promising to "hit them hard" after Iran launched missiles overnight at two U.S. air bases in Jordan in response to a U.S. attack on Iran’s Larak Island.

Gold prices pulled back on Monday as investors continued to reassess the Federal Reserve’s rate outlook following Chair Kevin Warsh’s hawkish inflation message, while rising oil prices added to inflation concerns.

Despite the latest pullback, gold remains about 10% higher in August and is heading for its strongest monthly gain since January.

As of 08:05 ET (12:05 GMT), XAU/USD rose marginally to $4,458.30 an ounce, while Gold Futures declined 0.4% to $4,509.41. XAG/USD rose 1.5% to $67.37 an ounce, while XPT/USD fell 0,5% to $1,813.69. The US Dollar Index fell 0.2% to 99.5.

The U.S. dollar on Friday hit a near two-week high after Federal Reserve Chair Kevin Warsh’s first keynote address at the Jackson Hole conference was perceived as hawkish. Traders added to their expectations of a central bank rate hike in September after Warsh said underlying inflation trends had not "meaningfully improved." 

The greenback was also set for a weekly rise of about 1%, wiping out all the losses from the previous week that was sparked by the so-called debasement trade amid a steep sell-off in U.S. Treasury bonds.

At 15:36 ET (19:36 GMT), the U.S. dollar index, which tracks the world’s premier currency against a basket of six major peers, climbed 0.5% to 99.65, its highest level since August 18. 

Bitcoin edged lower on Monday, pressured by hawkish comments from Federal Reserve Chair Kevin Warsh, which pushed up expectations for rising interest rates, and renewed military action between the U.S. and Iran, which sent oil prices surging.

Bitcoin fell 1.3% to $77,915.1 by 09:51 ET (13:51 GMT). The world’s largest crypto hit an intraday low of $77,000.0. 

Still, Bitcoin was set to add nearly 24% in August after a major rebound rally in recent weeks.