GBP struggles around $1.3900 despite triangle breakout, as the US dollar picks up bids and resumes Tuesday’s uptrend. Ongoing Brexit concerns over the Northern Ireland border issues and strong US economic data also weigh on the cable. The dollar’s bounce on Tuesday put pressure on the euro, which dropped to $1.2021 and threatened to breach important chart support in the $1.1995/1.2000 area. The dollar indexwas last at 91.319 after rising as high as 91.436 earlier in the session, its highest since April 19.The earlier bounce was partly prompted by comments from U.S. Treasury Secretary Janet Yellen that rate hikes may be needed to stop the economy from overheating. Yellen later downplayed their importance, but even the slightest mention of U.S. tightening has an outsized impact in markets that have become so dependent on monetary stimulus.Three Fed officials spoke on Wednesday, with Chicago Federal Reserve Bank President Charles Evans saying that while he was more optimistic about U.S. economic growth than he was a few months ago, he expects monetary policy to stay super-easy for some time.