(Reuters) - The United States and Britain launched strikes from the air and sea against Houthi military targets in Yemen in response to the movement's attacks on ships in the Red Sea, a dramatic escalation of the Israel-Hamas war in Gaza.

Oil climbed [MKTS/GLOB] and stock markets tensed on the news.

Comments from investors and analysts:

KHOON GOH, HEAD OF ASIA RESEARCH, ANZ, SINGAPORE

"I think at this stage, it's difficult to predict. Whilst the attacks have already seen disruptions and diversions of shipping and that has already caused quite a sharp jump in shipping freight rates just in the last few weeks, if this strike is able to...resolve the issue and shipping lanes can be secured again and things normalise, then that'll be positive as we'll see a normalisation of freight rates.

"I think the concern is that if this starts to escalate... which will cause a potential spike up in oil price in particular, and further disruptions in shipping lanes.

"Markets are taking a wait-and-see approach for the time being, hence we're not seeing too much of a reaction. If we see a massive escalation of the situation...then the traditional flight-to-safety will see U.S. Treasuries, safe-haven currencies like yen and Swiss franc benefit."

SHANE OLIVER, CHIEF ECONOMIST, AMP (OTC:AMLTF), SYDNEY

"The U.S. and UK launching air strikes on Houthis in Yemen is adding to the risk of Iran being directly drawn into the conflict which would threaten oil supplies.

"The creeping widening in the Israel/Hamas conflict poses a risk to global growth and inflation, for example Houthi attacks on Red Sea shipping adding to transport costs as ships have to go around Africa.

"A weaker patch is often evident into February or March after seasonal strength from October. While we expect shares to provide reasonable returns this year, they are likely to be more constrained and vulnerable than last year and worries about delays in rate cuts, recession and geopolitics could drive a deeper first half pullback than seen last year."

ROB CARNELL, ASIA-PACIFIC HEAD OF RESEARCH, ING, SINGAPORE

"When we got in this morning after what was fairly disappointing U.S. inflation data, you'd have expected bond yields to spike higher on that. In fact, they did the opposite. That's probably a reaction to what's been happening in the Middle East with the U.S., UK air strikes on the Houthis. There will be a shift back towards risk aversion. This hasn't fully blossomed out into a proper risk-off mode.

"I think people are looking for a little bit of safety at the moment. Possibly, also, coming ahead of this weekend's Taiwan election, most people are just thinking 'maybe I want to take a little bit of risk off the table', and that's maybe a factor as well. So I think the bond market's probably the clearest indication of where things are going."